#include "FLOAT.h"

FLOAT F_mul_F(FLOAT a, FLOAT b) {
	//nemu_assert(0);
	 return (FLOAT)(((long long)a * (long long)b) >> 16);
}

FLOAT F_div_F(FLOAT a, FLOAT b) {
	/* Dividing two 64-bit integers needs the support of another library
	 * `libgcc', other than newlib. It is a dirty work to port `libgcc'
	 * to NEMU. In fact, it is unnecessary to perform a "64/64" division
	 * here. A "64/32" division is enough.
	 *
	 * To perform a "64/32" division, you can use the x86 instruction
	 * `div' or `idiv' by inline assembly. We provide a template for you
	 * to prevent you from uncessary details.
	 *
	 *     asm volatile ("??? %2" : "=a"(???), "=d"(???) : "r"(???), "a"(???), "d"(???));
	 *
	 * If you want to use the template above, you should fill the "???"
	 * correctly. For more information, please read the i386 manual for
	 * division instructions, and search the Internet about "inline assembly".
	 * It is OK not to use the template above, but you should figure
	 * out another way to perform the division.
	 */

	//nemu_assert(0);
        int ss=1;
        if(a<0) a=-a,ss=-ss;
        if(b<0) b=-b,ss=-ss;
        int ans=a/b;
        //int mm=a%b;
        a=a%b;
        int i;
        for(i=0;i<16;i++){
            a<<=1;
            ans<<=1;
            if(a>=b){
                a-=b;
                ans++;} 
        }
        return ans*ss;
}

FLOAT f2F(float a) {
	/* You should figure out how to convert `a' into FLOAT without
	 * introducing x87 floating point instructions. Else you can
	 * not run this code in NEMU before implementing x87 floating
	 * point instructions, which is contrary to our expectation.
	 *
	 * Hint: The bit representation of `a' is already on the
	 * stack. How do you retrieve it to another variable without
	 * performing arithmetic operations on it directly?
	 */

	//nemu_assert(0);
	//return 0;
          int b = *(int*)&a;
          int ss = b >> 31;
          int exp = (b >> 23) & 0xff;
          int x = b & 0x7fffff;
		  if(exp==0) return 0;
          x += 1 << 23;
	      exp -= 134;
	      if(exp < 0) x >>= -exp;
	      if(exp > 0) x <<= exp;
	      if(ss)  return -x;
	      else  return x;
}

FLOAT Fabs(FLOAT a) {
	/*nemu_assert(0);
	return 0;*/
        if(a<0) a=-a;
        return a;
}

/* Functions below are already implemented */

FLOAT sqrt(FLOAT x) {
	FLOAT dt, t = int2F(2);

	do {
		dt = F_div_int((F_div_F(x, t) - t), 2);
		t += dt;
	} while(Fabs(dt) > f2F(1e-4));

	return t;
}

FLOAT pow(FLOAT x, FLOAT y) {
	/* we only compute x^0.333 */
	FLOAT t2, dt, t = int2F(2);

	do {
		t2 = F_mul_F(t, t);
		dt = (F_div_F(x, t2) - t) / 3;
		t += dt;
	} while(Fabs(dt) > f2F(1e-4));

	return t;
}

